Take your minimum velocity and maximum velocity, run them through a ballistics program. Look at the difference in the drop values for both velocities at 600 and 1000 yards, it will give you an idea if you can hold your shots in the X ring.
My method as well to show the "effect" of a higher ES/SD to folks that don't appreciate what you're trying to achieve.
I want single digit SD if at all possible for the longer range guns. I find it easier to achieve in the longer barreled rifles, whereas I really don't sweat it than much in the 300 yds and under hunt rifles/carbines.
Which doesn’t account for barrel harmonics.
You both are assuming the barrel is “pointing” in the exact same place when the bullet exits to lay that much weight to velocities to calculate drop
In a proper node, higher velocity rounds exit quicker when the muzzle is pointing lower, but drop less
Lower velocity rounds exit later when the muzzle is pointing higher, but drop more
The cumulative effect is minimal vertical dispersion and is the characteristic of the best load
